Performance of the Token Bus for Time Critical Messages in a Manufacturing Environment

The delivery of critical messages within delay constraints is an important criterion in the design and management of computer communication networks in the manufacturing environment. This environment is generally characterized by a large number of disparate data groups, each with their own network statistics and delivery requirements. The study and analysis of the token passing bus is of particular importance to this environment due to its selection by the Manufacturing Automation Protocol (MAP) as the standard at the physical and data link layers. In this paper we apply an analytical model to predict the performance of the token bus network in satisfying the delay constraints of frames assigned to the highest priority class. Several examples are given which illustrate the application of the analytical work and also give insight into the relationship between network performance and parameter values of the protocol. Results from a discrete event simulation study of the token bus are included for comparison.